Automatic speed-control system for railways



F. L. DODGSON AU'I'OIITIC SPEED CONTROL SYSTEM FOR RAELWAYS June 23, 1925. 1,543,641

Filed Feb. 2, 1917 4 Sheets-Sheet 1 MT t 7 in 0mm 1 June 23, 1925. 1,543,641

F. L. DODGSON AUTOMATIC SPEED CONTROL SYSTEM FORRAILWAYS Filed Feb. 3, 1917 4 Sheets-Sheet 2 %MW ,4 TTO NH June 23, 1925. 1,543,641

'F.' L. DODGSON AUTOIATIG sr'mm 'coNTRcSL SYSTEI FOR animus Filed Feb. 2 1917 4 shgetse-sheef 4 Patented June 23, 1925 "UNITE STATES PATENT OFFICE.

FRANKL. noneson, or nocnns'rnn, ronnnssrenon GENERAL RAILWAY SIGNAL COMPANY, ononrns, NEW YORK, A CORPORATION OF NEW YORK.

AUroivrATr-o SPEED-CONTROL sYsrn FOR R ATLWAYS.

Application filed February 2, 1917. Serial No. 146,242.

One of the objects ott'his invention is to devise an arrangement and construction'of' parts for automatic speed control systems so that the power conductor, such .as the third rail'or trolley wire, used in electrically propelled roads, may also be used as part of the means torcontrolling the speed control system.

A further object of the invention is to c levise an automatic'speed control system which is especially adapted for use on electrically propelled roads and in which the devices and conductors used for supplying propulsion current to the trains may also be used for-controlling the speed control apparatus.

A still further object or the invention is to provide a means of control fo1*.autoinat'ic speed control systems such that .the control influence determining the operation of the speed control apparatus may be communicated to a train at all points in its travel, thereby enabling the automatic speed 'control apparatus on a train .to immediately ,re-

spond to any change intratlicconditions ahead of that train. G

Other objects and advantages of th s 1nvention will appear more fully hereinafter as the description voffthe invention progresses.

In describing the invention in detail, reference is made to the accompanying drawings in which is illustrated certain physical embodiments of my invention, in which like reference characters .refer to like parts in the several views, ancl in which;

Fig. 1 is a dia rammatic illustration of one physicalembodiment of the invention as :applied to electrically operated roads using .a third mail, this figure illustrating ina conventional manner the trackway .circuits and the circuits and apparatus on a similar to Fig. way circuits.

train; Fig. 2 is a diagrammatic illustration of one form which-the speed control apparatus carried by the vehicle may take; Fig. 3 is a view similar to-Fig. -2showing a modified arrangement of the car carried apparatus; and Fig. '4: is a diagrammatic View 1 showing modified track-- Referring to the accompanying drawings, and more particularly to Fig. 1,-the numerals 1 and 2 designate the track rails of an ordinary railroad track, the separate rail sections thereofibeing suitably bonded together. This railroad track is divided into electrically isolated blocks or track sections, and in "the particular arrangement shown in Fig. 1, both of the track rails 1 and 2 are divided at intervals by insulating joints 3 into a number of blocks A, B, etc. The reference-character 4 designates the well known impedance bonds which are used in accordance with the well known practice to permit propulsion current toflow along the track rails 1 and 2 from one block to another and at the same time to prevent the current applied to track rails'ior signaling purposes from passing from .one block to another. This signaling current is supplied from a transmission line 5 connected to a suitable source of alternating, current, as a generator 6. The electrical connections and devices associated witlreach block are the same and for convenience these connections and devices for the several blocks shown are given the same reference characters with distinguishing exponents. Associated with each track section or block is a track transformer 7, the secondary of which is connected across the track rails 1 and 2 at one end of thecorresponding block in the usual manner; and associated with each block is a track relay 8 of suitable construction capable of responding to alternating current which is also connected across the track rails 1 and 2. Each of these track. relaysS is provided with armatures.orcontactlingers 12 and '13 which are illustrated according to established con vention.

Extending along the railroad track is a power conductor, which in the particular embodiment ofjthe invention illustrated is shown as a third rail T, which is supplied with propulsion current from .a suitable source, as a direct current generator'9. This third rail T issepar'ated into sections a, c,

etc., which are electrically isolated as regards the signaling current used but which are electrically continuous as regards the propulsion current. This segregation may be accomplished in various ways but, in the particular embodiment of the invention illustrated, suitable insulating joints or con nections are inserted at the proper points in said third rail T, and impedance bonds or connections 11 of suitable construction are connected around each of said insulating joints. It will be apparent to those skilled in the art that the impedance bonds or connections 11 will permit the flow of the direct current used for propulsion purposes from one third rail section to another, while at the same time preventing such flow of the alternating current used for signaling purposes.

Associated with each of the blocks is a transformer 14: for supplying signaling cur rent to the third rail sections, the secondary of this transformer being provided with two taps or connections by means of which two different voltages may be used. The connections between the secondaries of these transformers 14; and the third rail sections a, b, 0, etc., are controlled by tl e armatures of the track relays 8, and since these connections are the same for each of the blocks, they will be given corresponding reference characters with distinctive exponents and will be set forth in detail hereinafter in the description of the operation.

The vehicle or train adapted to travel on the track is shown diagrammatically as comprising two pairs of wheels 15-15, 1616 and axles 17 and 18 connected by suitable side-bars 19; and this vehicle is shown as provided with a contact shoe S of suitable construction which is adapted to make electrical contact with the third rail T, there being in practice two contact shoes, one on each side of the vehicle. In accordance with the established practice, the vehicle is shown as propelled by an electric motor M which is included in a circuit extending from the wheels and axles through controlling devices indicated diagrammatically at 20 to the contact shoe. The speed control apparatus is illustrated in Fig. 1 diagrammatically as a device K which may take various specific forms adapted for use in connection with the particular type of trackway circuits illustrated, one of these forms being shown in Fig. 2 and described more fully hereinafter. This speed control apparatus K is controlled by a car relay R which is so constructed and arranged as to be operated by alternating current. One terminal of the car relay R is connected by conductor 21, condenser 22 and conductor 23 to the contact shoe S, and the other terminal is connected by conductor 24:, impedance 25 and conductor 26 to the wheels and axles of the veprevent the direct current used for propulsion purposes from flowing to the car relay R, and it is apparent that if this car relay be made of such construction that direct current flowing through its coils of windings will have no improper influence, the condenser may be omitted. It is also apparent that other devices, such as transformers, may be used in place of the condenser 22 for performing its function. The purpose of the impedance 25 is to limit the flow of cur" rent at times through the car relay R to a certain amount for a certain voltage which will be insuflicient to cause an operationof the armatures of said car relay, as will be more fully explained hereinafter. The car relay is shown as provided with two armatures or contact fingers 27 and 28, one of which controls a normally closed circuit in cluding a suitable source of current 29 for governing the speed control apparatus K, and the other armature, together with conductors 30 and 31, controls a low resistance shunt around the impedance 25, for the purpose more fully explained hereinafter in the description of the operation.

One form of the speed control apparatus is shown in Fig. 2, which illustrates a con struction and arrangement of parts selected more with a View of rendering the principles and operation of the apparatus more easily understood than with the idea of showing the preferred construction suitable for practical use. In this diagrammatic construction illustrated, a worm gear 32 is secured to one of the car axles 17 and meshes with a worm wheel 33 fixed to a shaft 34 supported in suitable bearings (not shown). The shaft 3% drives another shaft 35supported in bearings 36 by means of meshing beveled gears 37 and 38. Secured to the shaft 35 is a yoke 39 carrying two weighted members 40, each of which is provided with a toothed sector engaging teeth in a sleeve ll slidable on the shaft 35, this sleeve 41 being urged to the right, opposing the tendency of the weighted members 4. 0 to move said sleeve, by a spring 42.

The shaft 35 is connected to another shaft 43 by a suitable form of universal coupling 4% and carried by this shaft l?) is a worm gear 45 arranged to mesh with a worm.

wheel a6 fixed to a cam shaft f? supported in suitable bearings l8, said cam shaft being provided with suitable means, as a weight 49 secured to said worm wheel as, tending to cause said cam shaft to assume a predetermined initial position. The shaft 43 carrying the worm i5 tends to move into mesh with the worm gear 46 due to gravity and mayberaised out of mesh by the energization of the solenoid 50, the core 51 of which is connected in some suitable manner to the shaft &3 so as to permit said hicle. The purpose of the condenser 22 is to shaft to be raised without interfering with its rotation. In the particular form of con nection between the core 51 of the solenoid and the shaft 43 illustrated in Fig. 2,

a collar or sleeve 52 loosely mounted on the shaft 43 is connected by pivot pins 53 to bifurcated arms straddling it and integrally connected or secured to said core 51. The cam shaft A? has fixed thereto two camshaped discs 54 and 55, hereinafter termed the cams, for the purposes more fully explained hereinafter.

Arranged parallel with the cam shaft t? is another shaft 56 supported in suitable bearings 57 which is caused to be turned through different angles in accordance with the movement of the sleeve 41, actuated by the weighted members 40, by means of some suitable connection, which is shown as comprising an arm 58 connected to said shaft and connected by rollers 59 and collars '60 to the slidable sleeve ll in any suitable or well known manner. Loosely mounted on the shaft 56 are arms 61 and 62, each carrying a freely revoluble roller '63 at their outer ends adapted to engage the edges of the cams 54 and 55. Fixed to the shaft 56, so as to turn therewith, are arms 64 and 65 which are connected by tensionsprings 6,6 to extensions of the arms 61 and '62; and each of the arms 64 and'65 is provided with an insulated contact pin 67 adapted to make electrical contact with the extension of the corresponding arm 61 or 62.

The speed control apparatus shown in Fig. 2 is illustrated as applied to a vehicle which is provided with air brakes of the well known construction, although it is apparent that the speed control apparatus illustrated is capable of use with the vehicles using other types of brakes. The construction and operation of the well known system of air brakes is known to those skilled in the art, and in the application of this invention to this system of brakes, it has been deemed sufficient to illustrate a portion of the usual train pipe 68 and an electrically controlled valve 69 of suitable construction for venting this train pipe and causing an application of the brakes as required. 1 The speed control apparatus illustrated in Fig. 2 is also shown as provided with a warning signal, which is shown as a whistle 70 adapted to be operated by compressed air and connected to a suitable source of compressed air, as the train pipe 68, the operation of said whistle being controlled by an electrically operable valve "-71 of suitable construction.

Assuming that the vehicle shown in 'Fig. 1 has a train control apparatus thereon of the type shown in Fig. 2, the operation of the system of speed control is zaszfollows: Assume the vehicle "to be occupying the block 13, as shown in Fig. 1 and about to 1 section 0.

enter the block C, and further assume both of the blocks C and D are not occupied by another train. The insulating joint or con nection 10 in the third rail T is located at such a distance back from the insulating joints 3 at the entrance to the block C that the shoe S carried by the vehicle will pass from the third rail section Z) to the third rail section 0 before the first pair of wheels and axle of that vehicle pass into the block C. Y

When the shoe of the vehicle passes on the third rail section 0, and before the first pair of wheels and-axle of the vehicle enter the block C, alternating current of a voltage equal to the voltage of the entire secondary of the transformer 14 is supplied to the car relay R along a circuit which may be traced as follows: Commencing at the third railsec-tion 0, conductor 72 armature 12 of the track relay 8 in its upper position, conductor 73 secondary of the transformer 14: conductor 74 track rail 2, through the wheels and axles of the vehicle, conductor '26, impedance 25, conductor 24, car relay R, conductor 21, condenser 22, conductor 23, and shoe S, back to the third rail section 0. The entire voltage of the secondary of the transformer 1 F, which for convenience is termed high voltage, is designed to send suflicient cur-rent through the car relay R, even with the impedance 25 included in series therewith, to cause the raising of the armatures of said car relay; consequently, the car relay will be energized sufiiciently 'to raise its armatures :or hold them in their raised position, in every case where high voltage is applied to 'a third rail section. With the car relay R energized and its armatures in the upper position, the parts of the speed control apparatus are in their normal condition and, except for imposing the limitation upon the maximum speed which the vehicle may attain, permit the vehicle to travel at the will of the operator. I l Vhen the first pair of wheels and axle enter the block C the track relay 8 is shunted and its armatures drop, the armature 12 interrupting the circuit hercinbefore traced for supplying high voltage to the third rail Under the particular traffic conditions assumed, that is, with the block D not occupied, the armatures of the track relay 8 of said block D are in their upper position, so that when the armature of the trackrelay 8 of the block C-drops, the voltage applied to the third rail section 0 is now that equalto only partof the secondary of the transformer 14 which is conveniently termed low voltage, the circuit beingas follows: Commencing at the third rail sect-ion a, conductor 72 armature 12 of the track relay 8 in its lower position, conductor 75 armature 13 of the track relay 8 in its Inn r light a green lamp (1, indlcatmg upper position, conductor 76 part of the secondary of the transformer 14 conductor 74?, track rail -2 of the block B through the wheels and axles of the vehicle, conductor 26, impedance 25, conductor 2%, car relay R, conductor 21, condenser 22, conductor 23, and contact shoe S back to the third rail section 0.

This low voltage is sufficient, when the impedance 25 in series with the car relay R is shunted, to hold or to raise the armatures of said car relay in their upper position, but is insufficient to raise these armatures from their lower position, when the impedance 25 is included in the car relay circuit. Under the particular conditions assumed, the armatures of the car relay It were in their upper position when the vehicle entered the block C, and consequently these armatures of the car relay remain in their upper position, and the speed control apparatus remains in its normal condition.

Suppose that when the vehicle enters the block 0, the block D is occupied, then the armature 13 of the track relay 8 would be in its lower position, thereby interrupting the supply of current to the third rail section 0; and in this way the armatures of the car relay R are caused to drop and set the speed control apparatus into operation.

Referring to Fig. 2, when the car relay It is deenergized and its armatures drop, a normally closed circuit supplying current to proceed, is interrupted, said circuit being as follows: Commencing at the battery 77, conductors 78, 79, 80 and 81, armature 82 in its upper position, conductor 83, lamp G, and conducto-rs 8 f, 85, 86 and 87 back to the battery 77. At the same time the dropping of the armature 82 to its lower position establishes a circuit for lighting the yellow light Y, indicating caution, said circuit being as follows: Commencing at the battery 77, conductors 78, 79, 80 and 81 armature 82 in its lower position, conductor 88, lamp Y, and conductors 89, 86, and 87 back to the battery 77.

When the armature 27 of the car relay R drops, it interrupts a normally closed circuit for energizing the solenoid 50, said circuit being traced as follows: Commencing at the battery 77, conductors 87, 86, 85, and 90, solenoid 50, conductor 91, armature 27 in its upper position, and conductors 92, 80, 79, and 78 back to the battery 77.

The deenergization of the solenoid permits the shaft 4-3 to drop and bring the worm 45 into mesh with the worm gear 46, thereby operatively connecting the cam shaft l7 by means of intermediate reduction gearing with an axle of the vehicle, so that as the vehicle travels the cam shaft 47 will be gradually turned in one direction or the other exactly in accordance with the distance traveled by the Vehicle. As the vehicle travels the weighted members 40 are thrown outward against the opposition of the spring 42 to a more or less extent depending upon the actual speed of the vehicle, and cause the arm 58 and the shaft 56 to be turned through an angle depending upon said actual speed. The turning movement of the shaft 56 is transmitted to the arms 61 and 62 by means of the springs 66, and as the actual speed of the vehicle increases these arms are moved toward their corresponding cams 54: and 55. The shape of the cam 54 is determined by the shape of the curve of permissive speed desired for the vehicle, and in general, since the desired curve of permissive speed corresponds to the safe braking curve of the vehicle, the shape of the cam depends upon the braking curve of the vehicle. More specifically, the shape of the cam is so selected that taken in connection with the path of movement of the roller 63 and the arm 61, and in connection with the actual speed of the vehicle corresponding to different positions of the arm 61, said arm will be prevented from assuming a position to the left. as shown in Fig. 2, corresponding to higher speeds, greater than the desired permissive speed for the vehicle at each point in its travel determined by the distance traveled by the vehicle since the cam shaft commenced to move. The shape of the cam is determined in the same way as the cam 5 f but with reference to a curve of permis sive speed which imposes lower permissive speeds than are im osed by the cam. The cam 54 is designec to cause an automatic application of the brakes whenever the actualspeed of the vehicle exceeds the permissive speed prescribed by this cam, and the cam 55 is intended to cause an operation of the warning signal at an interval prior to the automatic application of the brakes by the action of the other cam, which in terval will be sufficient to enable the engineer or motorman of the vehicle by a prompt attention to his duties to avoid an automatic application of the brakes. According tothe preferable arrangement, the shape of the cam 55 is such as to cause, for any given speed of the vehicle, the warning signal to be given at a predetermined time prior to the automatic application of the brakes by the action of the other cam 54.

In practice the blocks of a railway will vary in length, grades, curves and the like, and to obtain the most desirable control of the train in each of these different blocks, it is necessary to make some provision for modifying the action of the means, as the cams 54: and 55, which indicate or establish the permissive speed for the vehicle at different points in its travel. In the simplified illustration of this invention, no atpassing through a block.

,96 and 78 back to the battery 77,

tempt has been made to show how the permissive speed indicating means may be changed or modified so as to indicate the proper permissive speed at different points in blocks which vary in length, grades, and the like; but it is clearly understood that in the practical application of this invention it will be necessary to use some means for accomplishing this result.

Whenever the actual speed of the vehicle approaches the permissive speed at any point in the travel of the vehicle, after the speed control apparatus has been set into operation as hereinbefore described, the roller 63 carried by the arm 62 contacts with the edge of the cam 55 and causes a separation of the contact pin 6'? and the extension of said arm, thereby interrupting the circuit normally energizing the valve 71 controlling the warning signal 70, said circuit being traced as follows: Commencing at the battery 77, conductors 87, 93 and 94, extension of arm 62, contact pin 67, conductor 95, valve 71, and conductor If, after the sounding of the warning signal, the en gineer fails to properly control the speed of the train, and either continues at the same speed or causes an increase in the speed, the cam 54 will be moved to such a point by the travel of the vehicle, and the arm 61 will be moved to such a point by the speed responsive device, indicating the actual speed of the vehicle, that the contact pin 67 will be separated from the extension of the arm 61, thereby interrupting a normally closed circuit for supplying current to the valve 69, said circuit being traced as follows: Commencing at the battery 77, conductors 87, 93, and 97 extension of arm 61, contact pin 67, con ductor 98, valve 69, and conductors 99, 79, and 78 back to the battery 77.

The deenergization of the valve 69 acts to vent the train pipe 68 and cause an automatic application of the brakes in the well known manner. 7

It can be seen that even when the cams 54L and 55 are in their normal or initial position shown in the drawing, the actual speed of the vehicle can not exceed a certain predetermined speed without causing a sounding of the warning signal and a later application of the brakes. In this way the speed control apparatus shown acts to impose a limitation upon the maximum speed at which the vehicle may travel at any time in The apparatus may be arranged and constructed so that this maximum permissive speed is the same for each block or different for different blocks, and if desired special. provisions may be made for limiting the maximum speed of the train through hazardous territory, such as down steep grades, around a sharp curve,

and the like; but in order to avoid unneccapable of accomplishing these results have not been shown, and as regards this particular invention, it is onlynecessary to point out that the above mentioned features and other features found desirable in automatic speed control of trains are applicable to systems embodying this invention.

The gradual movement of the cams 5e and 55 by the progress of the vehicle through the bloclrG, in cooperation with the speed responsive device, and the mechanism jointly controlled thereby, serves to impose a gradually decreasing limitation upon the speed at which the vehicle may travel as it progresses through the block C; and either due .to the manual control by the engineer, aided by the warning signal, or by the automatic operation of the apparatus, the vehicle may be brought to a stop or to a predetermined low speed by the time it reaches the end of the block C. I

If by the time the vehicle reaches the end of the block C, the train formerly assumed to be in the block D, moves out of said block D, high voltage will be supplied to the third rail section d, due to the fact that the armature 12 of the track relay 8 is in its upper position, so as to establish a circuit analogous to the circuit already traced in connection with the third rail section 0.,- and con sequently when the vehicle in question reaches the end of the block C and its contact shoe S engages with the third rail section (Z, the car relay R will be reenergized and its armatures raised to their upper position, since this high voltage is suflicient to restore the armatures of the car relay, even with the impedance 25 in series therewith. The restoring of the armatures of the car relay to their normally upper position extinguishes the yellow lamp Y and lights the green lamp, G, and also reenergizes the sole- 4 noid 50 and moves the worm 45 out of mesh with the worm wheel 46, whereupon the cam shaft 4:7 and the cams 5st and 55 are returned to their normal or initial position by the action of suitable means, as the weight 49.

As the vehicle progresses and enters the block D, the voltage applied to the third rail section at will depend upon whether or not the block E is occupied by another train at this time, and the car relay will be maintained ener ized, or will be deenergized, in accordance with the traffic conditions in the block E, in the same manner as hereinbefore explained in connection with the vehicle when it entered the block C.

Returning to the conditions where the vehicle has entered the block (land has had its speed control apparatus set into operation becauseof the presence of another train rear vehicle reaches the end of the block 0. Under these conditions, it can be seen that the facility of movement of the following train would be much improved if suitable arrangements were made to permit the following vehicle to immediately resume its speed without waiting until it had passed through the entire length of the block G. The trackway circuits illustrated in Fig. 1 do not provide such additional facility of movement, since under the particular conditions above pointed out, it can be seen that low voltage will be applied to the third rail section 0, and this low voltage being insuificient to restore the armatures of the. car relay R, the vehicle must continue under the control of its speed control apparatus until it reaches the end of the block C. The addition of certain apparatus to the track control apparatus, as shown in Fig. 3, enables the speed control apparatus on a ve hicle at any point in any block to be restored to its initial or normal condition as soon as the next block in advance is not occupied.

Referring to Fig. 3, the greater part of the apparatus shown therein is the same as shown in Fig. 2 and operates in the same manner. Upon the cam shaft 17, however, an idditional plate 100 is mounted having a projecting portion 101, corresponding in angular extent to a predetermined portion of the length of a block, such as the block C. For example, the projecting portion 101 of the plate 100 may have an angular extent on each side of its middle point equivalent to three fourths or more of the length of a block. This projecting portion 101 of the plate 100 serves to hold a contact finger 102 in electrical contact with a suitable contact 103 against the opposition of a spring 104; and these contacts control the shunt for the impedance 25.

The operation of the modified arrangement of parts shown in Fig. 8 is as follows Vhen a vehicle enters the block, as the block C, and the next block in advance, as the block D, is occupied by another train, the car relay R is deenergized and the speed control apparatus is set into operation in the same way as hereinbefore described, but the shunt around the impedance 25 is not immediately interrupted when the car relay R is de-neergized, and this shunt continues until the vehicle has traveled more than threefourths of the way through the block C. Consequently, if at any time before the vehicle has traveled three-fourths of the first part of a block, the next block ahead is cleared, low voltage is transmitted to the car relay R; and since the impedance 25 remains shunted, this low voltage is sufficient to restore the armatures of the car relay R to their upper position, thereby restoring the speed control apparatus to its normal condition. If the vehicle is not released from the dominance of the speed control apparatus before it has passed the threefourths or some other greater part of the length of the block, then the shunt around the impedance 25 is broken by reason of the fact that the plate 100 has turned far enough to allow the contact finger 102 to separate from the contact 103 under the action of the spring 10t, whereupon it is necessary to have high voltage applied to a third rail section in order to restore the armat-ures of the car relay. In this way it is assured that a vehicle can not continue to travel through a block and into another block occupied by another train and obtain an improper release from the dominance of its speed control apparatus. The possibility of this improper release under these circumstances is due to the fact that when a train occupies a block, it is possible, as can be seen from the trackway circuits shown in Fig. 1, for low voltage to be applied to the third rail section of that occupied block, so that, if the car relay of a following vehicle might be restored by this low voltage, an improper release would be obtained.

In Fig. 1 is shown a slightly modified arrangement of control circuits of the type shown in Fig. 1 for providing for the early release of a vehicle from the dominance of its speed control apparatus at some intermediate point in its travel through a block in the rear of an occupied block. In this modified arrangement of circuits, each of the track relays is provided with a special type of circuit controlling means which is illustrated diagrammatically and is capable of momentarily closing a. circuit when the track relay is energized, but which does not close this circuit when the track relay is deenergized. The particular means for accomplishing this momentary control of a circuit may be accomplished in different ways, either by a peculiar construction of the armature or contact finger of the track relay itself, or by the operation of some relay or device controlled by the track relay. In the simplified construction illustrated diagrammatically, adjacent to the armature 105 of the track relay 8 is shown a pivoted contacting member 106 urged to an intermediate posit-ion shown in Fig. t by a spring 107 and adapted to slip by the end of the armature 105 and assume this intermediate position when said armature attains its uppermost or its lowermost position. The armature 105 has a piece 108 of insulating material secured to its underface, so that during the downward movement of said armature the engagement with said contact member 106 does not cause a closing of the circuit.

Assuming the conditions above described, which make it desirable to release a vehicle from the dominance of its speed control apparatus at an intermediate point in a block, the operation of the modification shown in Fig. l is as follows: Assume the vehicle in question is atthe intermediate point inthe block B, and that the control relay of" this vehicle was deenergized at the time this vehicle entered said block 13, due to the presence of another train in the block C, and further assume that said another train moves out of the block C. Under these conditions high voltage is momentarily applied to the third rail section Z) along a circuit which may be traced as follows Commencing at the third rail section b, conductor 109, impedance 110, conductor 111, armature 112 of the track-relay 8- in itslowerposition, conductor 113, annature10'5 of the track relay S contacting with the contact member 106 during upward movement of said armature, conductors 114 and 115 secondary of the transformer 14 conductor 74 track rail 2, and thence through the wheels and axles of the vehicle through the control relay and contact shoe back to the third section. I

This momentary application of high voltage to the third rail section b is sufli cient to restore the armatur'es of the car relay B to their upper position whereupon they will be held in that position due to the low voltage applied to said third rail section by the circuit including the armature 12 of the track relay 8 in its lower position and the armature 13 of the track relay 8 in its upper position, which circuit can be easily traced by analogy to the similar circuit hereinbefore considered. The parts are so arranged and constructed that before the armature 13 of the track relay 8 is raised sufficiently to close the last mentioned circuit, the armature 105 breaks contact with the contact member 106 thereby avoiding any objectionable short circuits; The impedance 110 included in the" circuit for momentarily applying high voltage to a third rail section, is designed to limit the flow of current to said third rail section to such an amount that only suflicient current could be supplied to one car relay to cause it to be restored, thereby avoiding apossibility of improperlyrestoring the car relay of a vehicle which entered a block occupied by another train waiting for the block in advance tobecome vacant.

From the foregoing it'can be seen that in the system embodying this invention the presence of a train on the track causes an influence to exist throughout a certain space or region behind that train, which may be called a zone of influence, and that a following train entering this zone of influence has its speed automatically restricted in accordance with its location in this zone, that is, as the following train advances into the zone its speed must be gradually decreased as it approaches closer to the forward end of the zone. In the modifications shown in Figures 3* and 4, the speed limitation on the follow ing train as it enters the zone of influence is automatically removed when the following train advances and causes the zone of influence to'advance correspondingly, the following train, however, after the removal of the gradually decreasing restriction upon its speedin accordance with its location in the zone, being prevented from exceeding a certain maximum speed which the following train should not exceed when it enters the zone again in its advanced. position.

Various modifications other than those illustrated and described and which utilize the features of this invention may be apparent to those skilled in the art. The speed control apparatus may take various forms other than the specific modification illustrated and described, and other arrangeinen'ts o'f trackway circuits involving-the same principles may be used if desired.- For example, while the invention has been illustrated and described as applied to double track railways in which trains normally run in only one direction on each track, the features of the invention are applicable to single track railways and to other special cases, the necessary adaptation requiring no more than the proper selection of well known means to cause the zone of influence to be established at the time and places desired.

Consequently, while I have illustrated and described certain physical embodiments of my invention and have explained the principles and operation thereof, nevertheless, I desire to have it clearly understood that these forms selected are merely illustrative and do not exhaust the possible physical embodiments of the idea of means underlying my invention.

1' clainr:

1. In a system for automatically control ling railway vehicles, in combination: a

railway track; a. power conductor extending along said track; means including said power conductor and responsive to the shunting action of the wheelsand les of a ve hic-le on said track for establishing a zone of influence behind said vehicle; and means on a following vehicle respoinling to the influence of said zone for limiting the speed of the following vehicle in accordance with its location in said zone if there is another vehicle. in advance within limited distance, said last mentioned means also automatically removing such speed restrictions if the: vehicle ahead advances more than said pre determined distance, but only if the intervening portion of. track is not occupied by another vehicle.

2. In a systenifor automatically control-- ling. railway vehicles, in combination: a railfor contacting with said power conductor;

and means on said following vehicle includmg a relay responsive to said distlnctive current for limiting the speed of said following vehicle in accordance with its location in said zone under dangerous traffic conditions and for automatically removing the speed limits under safe traffic conditions but only if there is no other train ahead in the same Zone.

3. In a system for automatically controlling railway vehicles, in combination: a railway track divided into blocks; a source of current and a track relay associated with each block; a power conductor extending along said track and divided into sections corresponding to said blocks which are elec trically independent as regards a signaling current but are electrically continuous as regards the propulsion current; means controlled by said track relays for controlling the supply of signaling current to the sections of said power conductor; and means on a vehicle responding to the signaling current applied to the respective sections of said power conductor for automatically imposing and removing restrictions on the speed of said vehicle dependent on traffic conditions in advance and its location in the respective blocks, said, speed restrictions being automatically removed in a block only if that block is not occupied by another train.

t. In a system for automatically controlling railway vehicles, in combination: a track and a vehicle therefor; a power con ductor for supplying propulsion current to said vehicle; means for supplying a distinctive signalling current to said power conduct-or; and means on the vehicle including an actual speed device responsive to said distinctive signaling current but not to said propulsion current for automatically enforcing predetermined restrictions on the speed of said vehicle, said last mentioned means on the vehicle being automatically restored to its initial condition upon reception of said signalling current but only if a predetermined portion of track in advance of the vehicle is not occupied.

5. In an automatic train control system, automatic train control apparatus for a railway vehicle including a movable permissive speed device, gearing connected to the wheels of the vehicle for moving said permissive speed device, a control relay on the vehicle adapted when deenergized to cause the permissive speed device to be moved towards its low r speed positions, impulse transmitting means partly on the vehicle and partly along the track and adapted to govern the control relay at all points in the travel of the vehicle, and track circuits for governing said impulse transmitting means to cause deenergization of the control nelay when the relay approaches within a predetermined distance from another vehicle ahead said control relay after de-energizat-ion thereof being again energized only if a predetermined portion of track in advance of the vehicle is not occupied.

6. In a system for automatically controlling railway vehicles, in combination: a power conductor extending along the track; means on the vehicle for imposing a gradually decreasing limitation on its speed in accordance with its progress along the track after having its operation initiated; and means controlled by the presence of another vehicle on the track and including said power conductor for initiating the operation of said first mentioned means at a predetermined point behind said another vehicle and for automatically restoring said appara: tus to its initial condition after said another vehicle advances, only if the intervening track is not occupied.

7. In a system for automatically controlling railway vehicles, in combination: a track divided into blocks; a source of current and a track relay associated with each block; a power conductor extending along the track; means for dividing said power conductor intosections corresponding to said blocks which are electricallyindependent as regards a signalling current and are electrically continuous as regards propulsion current the divisions of said power conductor being in the rear of the block divisions; means controlled by said track relays for controlling the supply of signalling current to the sections of said power conductor; and means responsive to saidsignalling current for imposing a restriction on the speed of a following vehicle in accordance with its location in the block in the rear of an occupied block and for automatically removing said restriction when the next block in advance becomes unoccupied only if there is no other train ahead in the same block.

8. In a system for automatically con trolling railway vehicles, in combination: a track; a power conductor extending along said track; means responsive to the presence of a vehicle on said track for supplying a distinctive signalling current to said power conductor throughout a. zone of limited extent in the rear of said vehicle; and means on a following vehicle responsive to said signalling current for imposing a restriction upon the speed of the following vehicle in accordance with its location in the Zone when no signalling current is supplied to the ower conductor and for removin said speed restriction when signalling current is re-supplied to s id power conductor only if there is no other train ahead in the same zone.

9. In a system for automatically control,- ling railway vehicles, in combination: a track; a power conductor extending along the t "2101:; means responsive to the presence of a vehicle on predetermined portions of said track for establishing a zone of influ ence behind said vehicle, said zone of influence advancing step by step as said vehicle travels from one predetermined portion of the track to another; and means including said power conductor for imposing a restriction on the speed of a following vehicle in accordance with its location in said zone, said means automatically removing said rcstriction upon an advancing of the zone only if there is no other train immediately ahead of the following vehicle within the limits of said Zone.

10. In a system for automatically controlling railway vehicles, in combination: a track divided into blocks; a power conductor extending along the track; means for dividing said power conductor into sections cor responding to said blocks which are electrically independent as regards adistinctive signalling current and are electrically continuous as regards propulsion current; means responsive to the presence of a train in a block for discontinuing the supply of signalling current to the section of the power conductor associated with the block next in the rear; a following vehicle; automatic speed control apparatus on said following vehicle having a cycle of operation; and

means on the following vehicle responsive to said signalling current for controlling the initiation and restoration of the cycle of operation of said speed control apparatus, the sections of the power conductor being overlapped with respect to the blocks to permit the apparatus on the vehicle to be influenced by a given section of the power conductor before entering the corresponding block.

11. In an automatic train control system, the combination with a track divided into blocks, of a power conductor extending along the track, means dividing said power conductor into sections corresponding to said blocks which are electrically independent as regards a distinctive signaling current and electrically continuous as regards propulsion current, means for supplying distinctive signaling current to the section of the power conductor associated with each block when the next block in advance is not occupied, automatic speed control apparatus on the vehicle having a cycle of operation and adapted when set into operation to control the speed of the vehicle in accordance with its location in 83611 block, and control means on the vehicle responsive to said distinctive si naling current for restoring said apparatus to its initial condition, said control means being-ineffective when the vehicle enters an occupied block.

12. In an automatic train control system, the combination with a track divided into blocks, of a power conductor extending along the track, means dividing said power conductor into sections corresponding to said blocks which are electrically independent as regards a distinctive signaling current and electrically continuous as regards propulsion current, means for supplying a high voltage signaling current to the section of the power conductor associated with each block when the corresponding block is not occupied, means for temporarily supplying said signaling current to a section when the next block in advance becomes unoccupied, and automatic speed control apparatus on a vehicle having its restoration controlled by such high voltage signaling current.

13. In an automatic train control system, the combination with a track divided into blocks each having a track circuit, a power conductor extending along the track and d ivided into sections corresponding to said blocks, impedance bonds connecting the sections of said conductor, means controlled by the track circuit of each block for supply-' ing an alternating signaling current of a predetermined character. to the section of the power conductor associated with the block next inthe rear, and automatic speed control apparatus and control means therefor on a vehicle adapted when set into operation to change gradually toward an ultimate condition and to be restored under the influence of said signaling current, said con trol means being automatically rendered incapable of responding to the influence of said signaling current when said apparatus has attained its ultimate condition.

14:. In an automatic train control system, the combination with a track divided into blocks each having a track circuit, of a power conductor extending along the track and divided into sections corresponding to said blocks, means electrically connecting said sections of the conductor for power current but isolating them for the distinctive signaling current, means associated with each section of said conductor and controlled by the track sections of the corresponding block and the next block in advance for successively supplying distinctive signaling current of different voltages to said section when these blocks are not occupied as the vehicle approaches and enters the corresponding block, and automatic speed control apparatus on a vehicle having its operation controlled by said signaling currents.

15. In an automatic train control system, the combination with a.- vehicle and train control apparatus therefar, of a relay on the vehicle responsive to alternating current for controlling said apparatus, a contact shoe on the vehicle, a partial circuit including said relay and terminating at the contact shoe and wheels of the vehicle, means included in said partial circuit "for permitting the passage of alternating current but pre venting the passage of direct current, and means controlled by said relay for varylng the impedance of said partial circuit.

16. In a speed control system for railway vehicles, a track, a vehicle thereon, a permissible speed device on the vehicle having a maximum speed position and a minimum speed position, means including continuous devices along the trackWay for normally holding said permissible speed devlce in its maximum speed position and means on the vehicle for moving said permissible speed device from its maximum speed position to its minimum speed position in accordance with the distance traveled by the vehicle.

17 In a speed control system for railway vehicles, a track, a vehicle thereon, an actual speed device on the vehicle, a permissible speed device on the vehicle having a maximum speed position and a minimum speed position, means including continuous devices along the traclnvay for normally holding said permissible speed device in its maximum speed position, means on the ve hicle for moving said permissible speed device from its maximum speed position to its minimum speed position in accordance with the distance traveled by the vehicle, means for retarding the vehicle, and means for actuating the retarding means when the actual speed of the vehicle exceeds the permissible speed corresponding to the posi tion of the permissible speed device.

18. In an automatic train control system for railroads, brake control apparatus on a vehicle including a changeable permissive speed device adapted to be connected to the Wheels of the vehicle, said apparatus acting to apply the brakes of the vehicle automatically Whenever its running speed exceeds the permissive speed limit set up by said permissive speed device, and means including sectionalized continuous devices along the track for normally maintaining said permissive speed device in a maximum speed position and for connecting it to the wheels of the vehicle depending upon the presence and absence of other vehicles ahead within a limited distance, said means permitting restoration of said permissive speed device to its maximum speed position after connection thereof to the Wheels of the vehicle, only it a predetermined portion of track in advance of the vehicle is not occupied.

19. In an automatic train control system for railroads having tracks divided into blocks, the combination With car-carried apparatus adapted to be operatively connected to the Wheels of the car and set up gradually reducing speed limits in accordance with the progress of the vehicle, of means associated with each block "for continuously supplying energy to the apparatus on a car in said block at all points therein only it the next block in advance is not occupied, said car-carried apparatus after being set into operation being re stored to its initial condition upon reception of energy but only if there is no other train in the same block.

20. In an automatic train control system for railroads having tracks divided into blocks, the combination with car-carried brake control apparatus tending to assume a speed limiting condition and normally restrained by the reception of control energy from the trackway, of means including sectionalized continuous inductors along the trackway for supplying such control energy to a vehicle at all points in a block provided the next block in advance is not occupied, said apparatus after operation thereof being restored to its normal initial condition by the reception of such control energy but only if there is no other train ahead in the same block.

21. A continuous indication signalling system, comprising a track divided into insulated block sections having track relays in closed track circuits, a vehicle travelling on said track having an electro-responsive device, means con-trolled by said track relays for continuously supplying energy from a wayside source to said electro-responsive de vice and discontinuing the supply of'such energy in accordance with tratfic conditions, train governing mechanism controlled by said electro-responsive device, means responsive to the travel of the vehicle for removing the control over said train governing mechanism by said electroresponsive device after the vehicle has traveled a predetermined distance Within a block under caution conditions, and means governed by said track relays for controlling said vehicle responsive means operative to restore control over said train governing mechanism by said electroresponsive device only when the vehicle is adjacent the entrance of a clear block.

22. A continuous indication signalling system comprising a track divided into insulated block sections having track relays in closed track circuits, a vehicle travelling on said track having an electro-responsive device, means controlled by said track relays for supplying energy from relatively stationary sources to said electro-responsive de vice, train governing mechanism controlled by said electro-responsive device, means responsive to the travel of the vehicle for removing the control over said train governing mechanism by said electro-responsive device, and means governed by said track relays for controlling said vehicle responsive means to restore control over said train governing mechanism by said electr c-responsivedevice only when the vehicle is adjacent the entrance of a clear block.

23. A continuous indication signalling system, comprising a track divided into insulated blocks having track relays in closed track circuits, a vehicle travelling on said track ha ving vehicle controlling means and electro-responsive devices normally governing said means, 'means responsive to the travel of the vehicle for removing said vehicle controlling means from the government of said electro-responsive device after the vehicle has traveled a certain distance under predetermined traffic conditions, and means governed by said track relays for controlling said vehicle controlling means by said electroresponsive devices only when the vehicle is adjacent the entrance of aclear block.

24-. A continuous indication signalling system, comprising a track divided into insulated blocks having track relays in closed track circuits, a vehicle travelling on said track having vehicle controlling means and having electro-responsive devices normally governing said means, means controlled by said track relays for continuously energizing said electro-responsivc devices under clear taliic conditions, means responsive to the travel of the vehicle for removing said vehicle controlling means from the government of said electro-responsive devices after the vehicle has traveled a certain distance under predetermined traflic conditions, and electro-responsive means governed by said track relays to restore control over said ve hicle controlling means by said electro-responsive devices only when the vehicle is adjacent the entrance of a clear block.

25 An automatic train controlling system comprising a track divided into insulated block sections having track relays in closed track circuits, a conductor parallel to the track divided into corresponding sections, means controlled by said track relays for supplying energy to said conductor sections and tie-energizing said sections in accordance with traffic conditions, a vehicle having a contact travelling on said conductor sections, an electrorcsponsive deviceconnected to said contact, train governing means controlled by said electro-responsive device and adapted to be set in operation when said device is deenergized, means responsive to the travel of the vehicle for removing said train governing means from the control of said electro-responsive device when the vehicle has traveleda predetermined distance subsequently to the deenergization of said electro-responsive device, and electro-responsive means connected to said contact for causing said vehicle responsive means to move away from its governing position and restore control over said train governing means by said electro-responsive device only when the vehicle is adjacent the entrance of a clear block.

with traffic conditions, a vehicle having an electro-respons1ve device controlled by said conductor, vehicle governing mechanism controlled by said electro-responsive device, means on said vehicle responsive to the travel thereof for removing said electroresponsive device from the control of said conductor after the vehicle has travelled a certain distance under predetermined traflic conditions, and automatic means to cause said vehicleresponsive means to change from its controlling condition only when the vehicle is adjacent the entrance of a clear block. 7

27. A continuous indication train controlling system, comprising a track having track relays in closed track circuits, a conductor parallel to the track, means controlled by the track relays for energizing saidconductor in accordance with t-raflic conditions, a vehicle having an electro-responsive device controlled by said conductor, vehicle governing mechanism controlled by said electroresponsive device, means on said vehicle responsive to the travel thereof for opening the circuit of said electro-responsive device after the vehicle has travelled a certain dis tance under predetermined traffic conditions, and means controlled by said conductor to cause said vehicle responsive means to change from its controlling condition only when the vehicle is adjacent the entrance of a clear block.

28. A continuous indication train controlling system, comprising a track divided into block sections, a vehicle travelling on said track, train controlling devices on said ve hicle, means controlled by ti'aflic conditions for continuously energizing said devices under clear conditions and for tie-energizing said devices under caution conditions, means controlled by the vehicle for preventing said devices from being recnergized after the vehicle has travelled a predetermined distance under caution conditions, and means for actuating said vehicle controlled means when the vehicle is adjacent the entrance of a clear block to permit said train controlling devices to -be reenergized.

29. A continuous indication train controlling system, comprising atrack divided into insulated block sections having track relay-s in closed track circuits, a conductor parallel to the track divided into corresponding sections, means controlled by said track relays for energizing said conductor sections in accordance with traffic conditions, a vehicle travelling on said track having a medium adapted to chan e in proportion to the travel thereof and having controlling mechanism governed by said medium, electro responsive means on said vehicle governing said medium, said electro-responsive means being controlled by said conductor section but being inell'ective when energized by the normal energy supplied by said conductor sections, and means controlled by the track relays for supplying said electro-responsive device with effective energy from said conductor sections only whenthe vehicle is ad jacent the entrance of clear blocks, whereby said medium is governed by said electroresponsive device only when the vehicle is adjacent a clear block.

30. In an automatic train controlling system, a track divided into insulated block sections having track relays in closed track circuits, a vehicle travelling on said track, an electroresponsive device on said vehicle, means governed by said track relays for controlling said electro-responsive device,

vehicle controlling means governed by said electro-responsive device and adapted to be set in operation when said device is deenergized, means responsive to the travel of the vehicle for removing said vehicle controlling means from the government of said electro-responsive device when the vehicle has travelled a predetermined distance subsequently to the de-energization 01 said electro-responsive device, and electro-responsive means on said vehicle controlled by said track relays for causing said vehicle responsive means to move away from its governing position and restore control over said vehicle controlling means by said electro-responsive device only when the vehicle is adjacent the entrance of a clear block.

FRANK L. DODGSON. 

